Are you using any proprietary Samsung software to manage this external drive? If so, then you may need to update that software.
What file system is on this external drive? The output of your "diskutil list" command makes it appear that it is possibly a MS filesystem, but it is also odd to see an EFI partition on the drive since I thought only macOS created such a partition when erasing a drive.
If you have installed some third party NTFS software to access the NTFS file system on this external drive, then booting into Safe Mode probably won't help since that software I believe changes macOS so that the built-in macOS NTFS driver is not used and the third party NTFS driver won't be loaded in Safe Mode.
Instead of trying to mount all volumes on that external drive, try only mounting the data volume using this command (replace "diskXsY" with the correct device identifier for the volume you wish to mount):
diskutil mount readOnly diskXsY
From the "diskutil list" output you posted earlier, the command would have been:
diskutil mount readOnly disk6s2
Keep in mind the device identifier for connected devices & drives can change each time you boot or reconnect a device/drive. So make sure to verify the device identifier before issuing any commands.
This command should mount the volume in "/Volumes" by default.
You can see all mounted volumes by using the following command:
mount
Before doing anything, you should verify the health of the external Seagate drive by running DriveDx (free trial period) and posting the complete text report here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar. If the drive is failing, then you must proceed very carefully since any attempts to access the drive may cause the drive failure to get even worse, perhaps to the point where even a professional data recovery service will be unable to recover any files. You will need to install a special USB driver in order to attempt to access the health information of the external drive.
If the drive is failing, then your options are very limited on how to proceed to recover the data since most utilities (even data recovery utilities) are not able to handle the I/O errors produced by a failing hard drive. Plus you usually only get one chance at recovering data from a failing hard drive even with proper software, so choose wisely how you proceed.
Assuming the external drive is healthy, then you should run First Aid again. This time even if the First Aid summary says everything is "Ok", click "Show Details" and scroll back through the report to see if any unfixed errors are listed. The First Aid summary is known to lie (personal experience).
FYI, when posting Terminal commands and Terminal output, please place them in the "Code Insertion" block using the icon which looks like "</>" in order to make the output easier to read...it will help to preserve the original formatting & make it easier to distinguish characters. Or post a screenshot of the Terminal window. Text is better since it can allow us to copy & paste the data & manipulate it if necessary, but we need to be able to easily view the output so a screenshot is better than nothing.
Also, when working with external drives, it is best to disconnect all other external devices so that they don't interfere and in order to ensure they are not included in any Terminal command output (you can use the "external" option when using "diskutil list" to limit the output to a specific drive making sure you don't miss something which can be obscured by another external drive/device):
diskutil list external
You should not be worried about the data on the external drive since that data should be part of your backup regimen if that data is important. People should always have frequent and regular backups of their computer and all external media (including the cloud) which contains important & unique data. Apple includes Time Machine with macOS to make this process very simple (not sure about the cloud data though). People can also use other backup options as well, or a combination of backup options. Of course this won't help you now, but it should minimize the chances of needing difficult troubleshooting procedures to access data on a corrupted volume....and hopefully it will be notice for others reading this thread.
Edit: Assuming the external Samsung drive is healthy and it contains a MS file system (NTFS, exFAT, or FAT32), then you may want to connect the drive to a Windows system to see if the data can be accessed or the file system repaired.
Also, while using First Aid, make sure to run First Aid on the physical drive as well to make sure the partition table is checked and is in good condition.
